I thought I would experiment, write and share a JQuery plugin. I have written simple plugins for applications, but this is a first time for a public release plugin. The plugin is designed to manipulate dates. For any date on the page, you can transform the date to show its real age. To overcome a few huddles, I will explain.

JavaScript DateTime is not a reliable source, for getting the current date. JavaScript runs on the clients machine, in turn it relies on the client system clock to be 100% correct. While this shouldn’t generally be an issue, it’s not reliable. So, to get the real date I am calling a .NET web service and returning JSON using JQuery’s built-in mechanism for handling this.

To return JSON from an ASMX service, JQuery can be setup like so:

I have simplified JQuery’s mechanism in the plugin, and by no means you don’t have to use this. However for my case, I wrapped it inside a function for ease. This is how it should be setup to request JSON from an ASMX web service. The web service will see in the request headers JSON is requested, and therefore return JSON. So how do we do this?

You can provide your own mechanism for getting the current date, but this shows how it works.

The function call to getJson() calls the web service, which returns an anonymous object. Notice that month is returning month – 1. Why is this? Well JavaScript date begins in January at Month 0, in .NET January begins at Month 1. So, we do a bit of correction there. The web service knows that an XML Request (Ajax Request) is being sent but also with the content type JSON. The web service is clever enough to know how to handle this async JSON request and will return a JSON object. The callback function returns a data object with our date. Do notice however that data.d is used. “.d” to access our returns object, as designed by Microsoft.

The plugin has the following options.

TodaysDate (optional): – this is a JavaScript Date object, to be set to the current date. (Default value sets the current date using JavaScript).

InsertMode (optional): – this controls how the age is inserted. (Default value is set to ‘append’).

CustomCompare (optional): – this takes a function to compare dates and return the number of years between them. (Default uses its own compare).

InsertMode consists of the following options.

‘replace’ – replace the date with the real age.

‘append’ – append the date with real age.

‘prepend’ – prepend the date with the real age.

In its simplist form:

Will display:

Although the example is a VS project, the JQuery plugin is not .NET specific.

Ok, I’ve slightly changed some of the behaviour of the script combining control. In addition it now combines, compresses, minifies and caches CSS files! The CSS can also be used to target certain browsers and versions. It can be used like this:

Combining JavaScript files. Why is this important? If you have for example 10 JavaScript files included on your website, that means the browser will make a separate request for each one of these files. Latency can be seen as an issue here. We aren’t maximising throughput.

This analogy can be compared to for example, a set of Traffic Lights. You may have seen it sometimes when traffic lights are not functioning correctly, or sometimes you’re in a queue and you’re saying “for god sake, the lights don’t stay green long enough.” So it may stay green for about 5 seconds, which is just enough time for you to pull down the hand brake, accelerate and go. In that time you may get about 5 cars though for example. Now lets say the lights go green for 10 seconds. Now you may expect to get 10 cars through, but you may get 15 through. The time to negotiate the hand brake, accelerating and stopping is less frequent, so we are maximizing throughput. Read on: http://sumo.sourceforge.net/docs/dkrajzew_TRAF9_AgentbasedTLS.pdf

This is the same for negotiating each request in our case. I have seen a lot of different ways of people achieving script combining. Most commonly and a good way is to use a Handler, that returns the combined result. I have a handler that works in a similar way, but it can be implemented in a more friendly manor using a Custom Server Control.

The control has other configurable properties, such as caching, minifying and compressing. They are all switched on by default. The code below will look familiar to the ASP.NET AJAX Script Manager, script combining, but the control I wrote gives you more control over caching, minifying and compressing (using GZip).